The present invention relates to a combinatorial weighing apparatus, and more particularly to a combinatorial weighing apparatus suitable for use in weighing and packaging articles of relatively large volumes.
Automatic combinatorial weighing apparatus include a plurality of weighing machines composed of hoppers supplied with articles to be weighed and weight detectors for measuring the weights of the articles charged into the weighing hoppers. The combinatorial weighing apparatus effects a combinatorial arithmetic operation to select a combination of weighing machines which give a total weight closest to a target weight within a preset allowable weight range, discharges the articles from the selected weighing machines, and supplies new articles into the emptied weighing machines. The above cycle of operation is repeated for a continuous automatic weighing operation. The articles are discharged in one batch from the weighing apparatus to a packing machine. No problem arises where the volumes of the articles discharged in one batch are small. However, relatively large volumes of articles tend to cause various problems due to a poor charging efficiency at the time the large-volume articles are put into cartons, bags and other containers. To increase the charging efficiency for articles of large volumes, it has been conventional to add many charging steps such as for vibrating or pressing the articles discharged from the weighing hoppers. Such additional charging steps result in a longer weighing and packing time, and require a larger space of installation of the overall weighing and packing system. The weighing apparatus has also suffered from troubles such as a bridge of articles in a discharge port since a large quantity of articles are rushed into the discharge port at one time.
One solution to the foregoing problems has been to use two weighing apparatus. One of the weighing apparatus weighs and discharges a number of articles which have a total weight smaller than a target weight. Thereafter, the other weighing apparatus corrects the weight of the remaining articles and discharges them. This system is based on the principle that articles can be charged more efficiently by being divided into two groups than by being vibrated and pressed in one batch. However, this system requires two article supply lines, with the result that the overall arrangement becomes large in size and takes up an inceased area for installation.